The Astrophysical Journal Letters· 2012Q1
GALACTOSEISMOLOGY: DISCOVERY OF VERTICAL WAVES IN THE GALACTIC DISK
- 308citations
- Q1SCImago
- 2012year
Short summary
Evidence for vertical waves, or a North-South asymmetry, in the Galactic disk has been found using star density and velocity data from the Sloan Digital Sky Survey.
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Key points
- A North-South asymmetry in stellar number density and bulk velocity has been observed in the solar neighborhood.
- Star density shows a deficit at ~400 pc and an excess at ~800 pc from the Galactic midplane.
- Bulk velocity profiles exhibit gradual trends and smaller-scale features across the midplane.
- The observed asymmetry resembles a wavelike perturbation intrinsic to the Galactic disk.
- This phenomenon may be caused by a satellite galaxy or dark matter subhalo passing through the disk, indicating a recent disk-heating event.
AI-generated from the title and abstract; the full text is not read.
Abstract
We present evidence for a Galactic North-South asymmetry in the number density and bulk velocity of solar neighborhood stars. The number density profile, which is derived from main-sequence stars in the Sloan Digital Sky Survey, shows a (North - South)/(North + South) deficit at |z| ~ 400 pc and an excess at |z| ~ 800 pc. The bulk velocity profile, which is derived from the Sloan Extension for Galactic Understanding and Exploration, shows a gradual trend across the Galactic midplane as well as smaller-scale features. We speculate that the North-South asymmetry, which has the appearance of a wavelike perturbation, is intrinsic to the disk. We explore the physics of this phenomenon through an analysis of the linearized Boltzmann and Poisson equations and through one-dimensional simulations. The perturbation may be excited by the passage of a satellite galaxy or dark matter subhalo through the Galactic disk, in which case we are witnessing a recent disk-heating event.
The authors' abstract, as published at the source. The Astrophysical Journal Letters, 2012 · DOI ↗
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Field: Instrumentation
InstrumentationPhysics and Astronomy